Non-horizontal discharge gates

ABSTRACT

According to some embodiments, a railcar comprises an underframe and at least two hoppers coupled to the underframe. Each hopper is configured to transport a lading and comprises a transverse slope sheet and a discharge gate. The transverse slope sheet is coupled to a first side of the hopper and extends at an angle downward towards the center of the hopper forming a transverse discharge opening. The discharge gate is coupled to a second side of the hopper. The discharge gate is operable to move between a closed position where the discharge gate extends downward towards the transverse slope sheet restricting discharge of lading arid an open position where the discharge gate facilitates lading discharge. The orientation of the discharge gate is non-horizontal.

RELATED APPLICATION

This application claims priority to U.S. Provisional Application Ser. No. 62/549,621, entitled “NON-HORIZONTAL DISCHARGE GATES,” filed Aug. 24, 2017.

TECHNICAL FIELD

Particular embodiments relate generally to railcars, and more particularly to non-horizontal discharge gates for railcars, such as hopper cars for carrying bulk materials.

BACKGROUND

Railway hopper cars transport and sometimes store bulk materials. Hopper cars generally include one or more hoppers which may hold cargo or lading during shipment. Hopper cars are frequently used to transport coal, sand, metal ores, aggregates, grain, and any other type of lading which may be satisfactorily discharged through openings formed in one or more hoppers. Discharge openings are typically provided at or near the bottom of each hopper to rapidly discharge cargo. A variety of door assemblies or gate assemblies along with various operating mechanisms have been used to open and close discharge openings associated with railway hopper cars.

Transversely oriented discharge openings and gates are frequently coupled with a common linkage operated by an air cylinder. The air cylinder is typically mounted in the same orientation as the operating gate linkage which is often a longitudinal direction relative to the associated hopper.

Longitudinally oriented discharge openings and doors are often used in pairs that may be rotated or pivoted relative to the center sill or side sills of a hopper car. Longitudinally oriented discharge openings and doors may be coupled with a beam operated by an air cylinder. The air cylinder is typically mounted in the same orientation as the operating beam which is often a longitudinal direction relative to the associated hopper. The operating beam may be coupled to the discharge doors by door struts that push. (or pull) the gates open or pull (or push) them closed as the air cylinder moves the operating beam back and forth.

Hopper cars may be classified as open or closed. Hopper cars may have relatively short sidewalls and end walls or relatively tall or high sidewalls and end walls. The sidewalls and end walls of many hopper cars are often formed from steel or aluminum sheets and reinforced with a plurality of vertical side stakes or support posts. Some hopper cars include interior frame structures or braces to provide additional support for the sidewalk.

SUMMARY

Railcars that carry commodities that are discharged from the bottom of the railcar typically use a slide gate mechanism to open gates to that permit the lading to flow out of the railcar using gravity. The gates may be opened manually of with the aid of externally applied mechanical tools. The car body outlet gate mounting frames are arranged along a horizontal plane and the slides operate in a horizontal direction in the longitudinal axis of the railcar.

The outlet gates are standard components within the railroad industry. Common nominal sizes are 13×42, 30×30, and 42×42. A typical hopper car may have two or three hoppers, with a gate for each hopper.

The in-plane orientation and the horizontal travel of the slides in the longitudinal direction dictate the overall length (OIL) of the railcar. The hopper slope angles are related to the commodity angle of repose. The outlet gates are spaced at a particular distance apart to provide room for each gate to open without interfering with the adjacent hopper.

Particular embodiments place each of the discharge gates in a separate plane. By placing the discharge gates in separate plane, the distance between discharge gates may be reduced, which may reduce the overall length of the railcar.

In particular embodiments, the car body outlet gate mounting frames are oriented at angles symmetric about the car transverse centerline. For example, discharge gates on the A side of the centerline of the railcar may be oriented in one direction, and discharge gates on the B side of the centerline may be oriented in another direction. In another embodiment, the car body outlet gate mounting frames are oriented at common angles from one end of the car to the other.

According to some embodiments, a railcar comprise an underframe and at least two hoppers coupled to the underframe. Each hopper of the at least two hoppers is configured to transport a lading. Each hopper comprises a transverse slope sheet coupled to a first side of the hopper. The transverse slope sheet extends at an angle downward and towards the center of the hopper forming a transverse discharge opening between the first side of the hopper and a second side of the hopper opposite the first side of the hopper. Each hopper further comprises a discharge gate coupled to the second side of the hopper. The discharge gate is operable to move between a closed position where the discharge gate extends downward towards the transverse slope sheet restricting discharge of lading through the transverse discharge opening and an open position where the discharge gate facilitates lading discharge through the transverse discharge opening. The orientation of the discharge gate is non-horizontal.

In particular embodiments, the discharge gate is pivotally coupled to the second side of the hopper and operable to swing between the open position and the closed position. The discharge gate may be pivotally coupled to the second side of the hopper proximate a ridge between the at least two hoppers. In some embodiments, the discharge gate is slidably coupled to the second side of the hopper and operable to slide between the open position and the closed position.

in particular embodiments, the discharge gate of a first hopper of the at least two hoppers is offset from horizontal at a different angle than the discharge gate of a second hopper of the at least two hoppers. The discharge gate of a first hopper of the at least two hoppers may open in a different direction than the discharge gate of a second hopper of the at least two hoppers. The discharge gate of the first hopper and the discharge gate of the second hopper may open towards each other. The discharge gate of the first hopper and the discharge gate of the second hopper may be coupled proximate a ridge between the first hopper and the second hopper.

In particular embodiments, the longitudinal distance between adjacent edges of the at least two discharge gates is less than the longitudinal length of the discharge gate.

According to some embodiments, a hopper car discharge gate apparatus comprises a transverse slope sheet for coupling to a first side of a hopper of railcar. When coupled to the hopper, the transverse slope sheet extends at an angle downward and towards the center of the hopper forming a transverse discharge opening between the first side of the hopper and a second side of the hopper opposite the first side of the hopper. The apparatus further comprises a discharge gate for coupling to the second side of the hopper. When coupled to the hopper, the discharge gate is operable to move between a closed position where the discharge gate extends downward towards the transverse slope sheet restricting discharge of lading through the transverse discharge opening and an open position where the discharge gate facilitates lading discharge through the transverse discharge opening. The orientation of the discharge gate is non-horizontal when coupled to the hopper.

In particular embodiments, the discharge gate comprises a pivotal coupling for coupling to the second side of the hopper and the discharge gate is operable to swing between the open position and the closed position. In some embodiments, the discharge gate comprises a sliding coupling for coupling to the second side of the hopper and the discharge gate is operable to slide between the open position and the closed position.

According to some embodiments, a railcar comprises an underframe and at least two hoppers coupled to the underframe. Each hopper of the at least two hoppers is configured to transport a lading. Each hopper comprises a transverse discharge opening between a first side of the hopper and a second side of the hopper opposite the first side of the hopper. Each hopper further comprises a discharge gate coupled to the hopper. The discharge gate is operable to move between a closed position where the discharge gate restricts discharge of lading through the transverse discharge opening and an open position where the discharge gate facilitates lading discharge through the transverse discharge opening. The orientation of the discharge gate is non-horizontal.

In particular embodiments, the discharge gate is pivotally coupled to the hopper and operable to swing between the open position and the closed position. The discharge gate may be pivotally coupled to the hopper proximate a ridge between the at least two hoppers. In some embodiments, the discharge gate is slidably coupled to the hopper and operable to slide between the open position and the closed position.

Particular embodiments of the present disclosure may provide numerous technical advantages. For example, particular embodiments may provide reduced railcar length. Reduced railcar length enables the unit train consist to accommodate more railcars in a given linear track, which increases overall rail system efficiency. Reduced railcar length also facilitates more railcars to be spotted in a siding or in a shipper's facility. These factors may reduce the number of locomotives, crew, and overhead needed to move a given amount of commodity. In addition, the reduced length may reduce the tare weight of each railcar unit. A reduced tare weight facilitates carrying more lading per railcar and may reduce the construction cost of each unit. Particular embodiments of the present disclosure may provide some, none, all, or additional technical advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the particular embodiments, and the advantages thereof, reference is now made to the following written description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic drawing showing a side view of an example hopper car;

FIG. 2 is a schematic drawing illustrating a side view of the ridges and center sill of an example hopper car;

FIG. 3 is a schematic drawing showing a side view of an example hopper car with non-horizontal discharge gates in the closed position, according to a particular embodiment;

FIG. 4 is a schematic drawing showing a side view of an example hopper car with non-horizontal discharge gates in the open position, according to a particular embodiment;

FIG. 5 is a schematic drawing illustrating a hinged non-horizontal discharge gate, according to a particular embodiment;

FIG. 6 is a schematic drawing illustrating a sliding non-horizontal discharge gate, according to a particular embodiment;

FIG. 7 is a schematic drawing illustrating another hinged non-horizontal discharge gate, according to a particular embodiment; and

FIG. 8 is a schematic drawing illustrating another sliding non-horizontal discharge gate, according to a particular embodiment.

DETAILED DESCRIPTION

Railway hopper cars generally include one or more hoppers which may hold cargo or lading (e.g., bulk materials) during shipment. Hopper cars frequently transport coal, sand, metal ores, aggregates, grain, plastic pellets, and any other type of lading which may be satisfactorily discharged through openings formed in one or more hoppers. Discharge openings are typically provided at or near the bottom of each hopper to rapidly discharge cargo. A variety of door assemblies or gate assemblies along with various operating mechanisms have been used to open and close discharge openings associated with railway hopper cars.

FIG. 1 is a schematic drawing illustrating a side view of an example hopper car. Hopper car 20 may carry bulk materials such as coal and other types of lading. Examples of such lading may include sand, metal ores, aggregate, grain, ballast, etc.

Hopper car 20 may be generally described as a covered hopper car. However, other embodiments may include open hopper cars or any other cars (e.g., gondola cars) suitable for carrying bulk lading. Hopper car 20 includes containers for transporting its lading, such as hoppers 22 with bottom discharge assemblies 24. Discharge assemblies 24 may be opened and closed to control discharge of lading from hoppers 22. As illustrated, hopper car 20 includes two hoppers 22. Particular embodiments of hopper car 20 may include one, two, three, or any suitable number of hoppers 22. Particular embodiments may include other containers for transporting lading, with or without discharge assemblies.

In particular embodiments, hopper 22 is configured to carry bulk materials and the interior walls of hopper 22 are generally sloped towards discharge assembly 24 to facilitate discharge of the lading. Multiple hoppers 22 may be separated by interior bulkheads.

In particular embodiments, hopper car 20 may include a pair of sidewall assemblies 26 and sloped end wall assemblies 28 mounted on a railway car underframe. The railway car underframe includes center sill 34 and a pair of sill plates 32. The pair of sill plates 32 provide support for sidewall assemblies 26.

Center sill 34 is a structural element for carrying the loads of the hopper car. Center sill 34 transfers the various longitudinal forces encountered during train operation from car to car.

Conventional hopper cars may typically have 2, 3 or 4 hoppers with a single sliding gate below the discharge opening of each hopper. The sloping interior walls of hopper 22 create a ridge between the discharge openings to guide the lading towards the discharge opening. The sloping walls may also be referred to as gate supports. Conventional hopper cars typically have tall ridges between hoppers 22. An example of a ridge is illustrated in FIG. 2.

FIG. 2 is a schematic drawing illustrating a side view of the ridges and center sill of an example hopper car. Hopper car 20 is similar to hopper car 20 described with respect to FIG. 1. Hopper car 20 includes two hoppers 22 with discharge assemblies 24. Transverse discharge gates 36 are operable to slide in the longitudinal direction of hopper car 20 to discharge the lading of hoppers 22 through the discharge openings of discharge assemblies 24.

The sloping interior walls of hopper 22 form ridge 37. Ridge 37 comprises two sloping edges between adjacent discharge gates 36 a and 36 b. Distance 38 is the distance between adjacent discharge gates 36 a and 36 b. Ridge 37 is widest at its bottom-most portion (i.e., distance 38). The two sloping edges extend upward where they join together, forming ridge 37.

The particular width of discharge gates 36, and the particular width and height of ridges 37 depend on the length and height of hopper car 20 and each hopper 22. In some conventional hopper cars, gates 36 may be four or five feet wide and ridges 37 may be four feet high, as one example.

Gates 36 are arranged in a horizontal plane and they slide horizontally along the longitudinal axis of hopper car 20. Distance 38 must be large enough that gate 36 a does not interfere with discharge from an adjacent hopper when the gates are opened. Thus, distance 38 must at least be greater than the width of gate 36.

A particular goal of rail operators is to reduce the overall length of a railcar. One way to reduce the overall length is to reduce the distance between discharge gates. Particular embodiments obviate the problems described above and include a railcar, such as a hopper car, with non-horizontal discharge gates. Particular embodiments place the discharge gates on separate, non-horizontal planes, which can reduce the distance between discharge gates.

Reduced railcar length enables the unit train consist to accommodate more railcars in a given linear track, which increases overall rail system efficiency. Reduced railcar length also facilitates more railcars to be spotted in a siding or in a shipper's facility. These factors may reduce the number of locomotives, crew, and overhead needed to move a given amount of commodity.

In addition, the reduced length may reduce the tare weight of each railcar unit. A reduced tare weight facilitates carrying more lading per railcar and may reduce the construction cost of each unit.

Particular embodiments are described with reference to FIGS. 3-6 of the drawings. Like numbers may be used for like and corresponding parts of the various drawings. Various features of the embodiments will be described with respect to hopper car 20 shown in FIGS. 1 and 2.

FIG. 3 is a schematic drawing showing a side view of an example hopper car with non-horizontal discharge gates in the closed position, according to a particular embodiment. Hopper car 20 is similar to hopper car 20 described with respect to FIGS. 1 and 2, except that discharge gates 46 are non-horizontal (as compared to horizontal discharge gates 36 of FIG. 2).

Hopper 22 comprises transverse slope sheet 45 and discharge gate 46. Transverse slope sheet 45 is coupled to a first side of hopper 22 and extends at an angle downward from the first side of hopper 22 forming a transverse discharge opening between transverse slope sheet 45 and a second side of hopper 22 that is opposite the first side. Discharge gate 46 is coupled to the second side of hopper 22. Transverse slope sheet 45 and discharge gate 46 collectively may be referred to as a discharge gate apparatus.

Discharge gate 46 is operable to move between a closed position and an open position. In the closed position, discharge gate 46 extends from the second side of hopper 22 downward to intersect with transverse slope sheet 45 blocking the transverse discharge opening and restricting the lading of hopper 22 from discharging through the transverse discharge opening. In the open position, discharge gate 46 facilitates the discharge of lading from hopper 22 through the transverse discharge opening.

Unlike gates 36 of FIG. 2 that are arranged in the same horizontal plane, discharge gate 46 a is arranged in a different plane than discharge gate 46 b which is arranged in a different plane than discharge gate 46 c. Because discharge gates 46 are arranged in different planes, operation of one discharge gate 46 does not interfere with operation of another discharge gate 46. For example, regardless of the length of discharge gate 46 a, opening discharge gate 46 a does not interfere with adjacent discharge gate 46 b.

In the illustrated example, discharge gates 46 comprise hinged discharge gates. An advantage of the non-horizontal orientation of discharge gates 46 is that hinged discharge gates may be used in some embodiments. For example, discharge gates 36 of FIG. 2 are horizontal sliding gates because the horizontal plane to which they are mounted does not provide enough ground clearance for a hinged gate. The non-horizontal orientation of discharge gates 46 facilitates affixing a hinge point higher above the ground, providing enough ground clearance for a hinged discharge gate.

Another advantage of the non-horizontal orientation of discharge gates 46 is that the distance 48 between discharge gates may be less than the distance for the same size discharge gates mounted in a horizontal plane. For example, for similarly sized discharge gates 36 and 46, the distance 48 in FIG. 3 may be less than the distance 38 in FIG. 2. The distance between gates is dependent upon the angles of the slope sheets, not the length of discharge gates 46. For example, increasing the slope sheet angle decreases the distance between discharge gates 46. A particular advantage is that a railcar with non-horizontal discharge gates may carry the same volume in a shorter length railcar than a railcar with horizontal discharge gates.

FIG. 4 is a schematic drawing showing a side view of an example hopper car with non-horizontal discharge gates in the open position, according to a particular embodiment. As illustrated, discharge gates 46 swing downward to the open position to discharge the lading (illustrated arrows). In the open positions, discharge gates 46 require less width between discharge gates than the horizontal discharge gates 36 in FIG. 2. The longitudinal distance between adjacent edges of two discharge gates is less than the longitudinal length of the discharge gate.

Although the example slope sheets and discharge gates are illustrated at a particular angle, other embodiments may comprise any suitable angle. As described above, varying the angles also varies the distance between discharge gates, which facilitates varying the overall railcar length.

As described above, the non-horizontal orientation of discharge gates 46 facilitates use of a hinged discharge door in addition to a sliding discharge door. The hinged discharge door is possible because the elevated mounting location provided by the non-horizontal orientation increases the ground clearance, which gives more space for discharge gate 46 to swing downward.

In the illustrated example, the hinge point for discharge gate 46 is positioned part of the way up the slope sheet towards ridge 37. Other embodiments may minimize the distance between discharge gates by positioning the hinge point closer towards ridge 37. An example is illustrated in FIG. 5.

FIG. 5 is a schematic drawing illustrating a hinged non-horizontal discharge gate, according to a particular embodiment. FIG. 5 is a zoomed in view of discharge gates 46 illustrated in FIGS. 3 and 4. Discharge gates 46 are offset from horizontal by a particular angle. In some embodiments, the particular angle may depend on the intended lading for the hopper car.

Discharge gates 46 are configured to prevent lading from exiting the hopper in the closed position (A). To discharge the lading, discharge gates 46 swing to the open position (B) (illustrated as dashed lines). In the illustrated example, the hinge point of discharge gate 46 is located close to the ridge to minimize the distance between discharge gates 46.

Although the previous examples illustrate hinged gates, other embodiments may include other forms of discharge gates, such as a sliding gate. An example is illustrated in FIG. 6.

FIG. 6 is a schematic drawing illustrating a sliding non-horizontal discharge gate, according to a particular embodiment. Sliding discharge gates 46 are located in a non-horizontal plane. Sliding discharge gates 46 are configured to slide from the closed position. (A) to the open position (B) (illustrated by dashed arrows). In these embodiments, the width of discharge gate 46 is no more than half the distance to the ridge. Even so, the distance between discharge gates 46 in the non-horizontal orientation is less than the distance between similarly sized discharge gates in a horizontal orientation.

The previous examples illustrate multiple discharge gates all opening in the same direction. Some embodiments may include discharge gates that open in opposite directions, such as discharge gates that open in opposite directions on each side of a transverse centerline of the railcar. Examples are illustrated in FIGS. 7 and 8.

FIG. 7 is a schematic drawing illustrating another hinged non-horizontal discharge gate, according to a particular embodiment. FIG. 7 is similar to FIG. 5, except that both discharge gates 46 are hinged near the same ridge and open towards each other. In FIG. 5, the discharge gates are oriented in separate, non-horizontal but parallel planes. The discharge gates in FIG. 7 are oriented in separate, non-horizontal and intersecting planes.

In a two-hopper railcar, for example, the example of FIG. 7 may efficiently minimize the distance between discharge doors. Because of the non-horizontal orientation, the discharge doors may be located side-by-side with little space between them. A similar example is illustrated in FIG. 8.

FIG. 8 is a schematic drawing illustrating another sliding non-horizontal discharge gate, according to a particular embodiment. FIG. 8 is similar to FIG. 6, except that discharge gates 46 slide towards the same ridge. Because of the non-horizontal orientation, the discharge doors may be located side-by-side with little space between them.

The example discharge gates described herein may be operated manually, pneumatically, electrically, or by any other suitable operating mechanism. The particular operating mechanism is not illustrated.

Although transverse slope sheet 45 and discharge gate 46 appear to intersect at right angles near the longitudinal center of hopper 22 in the illustrated examples, in some embodiments the location and angle of intersection may vary. For example, discharge gate 46 may be oriented at a steeper angle than transverse slope sheet 45, or vice versa.

Although the components in FIGS. 1-8 are described with respect to a particular hopper car with a particular number of hoppers, particular embodiments may include any suitable type of railcar with any suitable number of discharge gates.

Although particular embodiments and their advantages have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the embodiments. 

1. A railcar comprising: an underframe; at least two hoppers coupled to the underframe, each hopper of the at least two hoppers configured to transport a lading and each hopper comprising: a transverse slope sheet coupled to a first side of the hopper, the transverse slope sheet extending at an angle downward and towards the center of the hopper forming a transverse discharge opening between the first side of the hopper and a second side of the hopper opposite the first side of the hopper; a discharge gate coupled to the second side of the hopper, the discharge gate operable to move between a closed position Where the discharge gate extends downward towards the transverse slope sheet restricting discharge of lading through the transverse discharge opening and an open position where the discharge gate facilitates lading discharge through the transverse discharge opening; and wherein the orientation of the discharge gate is non-horizontal.
 2. The railcar of claim 1, wherein the discharge gate is pivotally coupled to the second side of the hopper and operable to swing between the open position and the closed position.
 3. The railcar of claim 1, wherein the discharge gate is pivotally coupled to the second side of the hopper proximate a ridge between the at least two hoppers.
 4. The railcar of claim 1, wherein the discharge gate is slidably coupled to the second side of the hopper and operable to slide between the open position and the closed position.
 5. The railcar of claim 1, wherein the discharge gate of a first hopper of the at least two hoppers is offset from horizontal at a different angle than the discharge gate of a second hopper of the at least two hoppers.
 6. The railcar of claim 1, wherein the discharge gate of a first hopper of the at least two hoppers opens in a different direction than the discharge gate of a second hopper of the at least two hoppers.
 7. The railcar of claim 6, wherein the discharge gate of the first hopper and the discharge gate of the second hopper open towards each other.
 8. The railcar of claim 6, wherein the discharge gate of the first hopper and the discharge gate of the second hopper are coupled proximate a ridge between the first hopper and the second hopper.
 9. The railcar of claim 1, wherein the longitudinal distance between adjacent edges of the at least two discharge gates is less than the longitudinal length of the discharge gate.
 10. A hopper car discharge gate apparatus, the discharge gate apparatus comprising: a transverse slope sheet for coupling to a first side of a hopper of railcar, when coupled to the hopper the transverse slope sheet extends at an angle downward and towards the center of the hopper forming a transverse discharge opening between the first side of the hopper and a second side of the hopper opposite the first side of the hopper; a discharge gate for coupling to the second side of the hopper, when coupled to the hopper the discharge gate is operable to move between a closed position where the discharge gate extends downward towards the transverse slope sheet restricting discharge of lading through the transverse discharge opening and an open position where the discharge gate facilitates lading discharge through the transverse discharge opening; and wherein the orientation of the discharge gate is non-horizontal when coupled to the hopper.
 11. The discharge gate apparatus of claim 10, wherein the discharge gate comprises a pivotal coupling for coupling to the second side of the hopper and the discharge gate is operable to swing between the open position and the closed position.
 12. The discharge gate apparatus of claim 10, wherein the discharge gate comprises a sliding coupling for coupling to the second side of the hopper and the discharge gate is operable to slide between the open position and the closed position.
 13. A railcar comprising: an underframe; at least two hoppers coupled to the underframe, each hopper of the at least two hoppers configured to transport a lading and each hopper comprising: a transverse discharge opening between a first side of the hopper and a second side of the hopper opposite the first side of the hopper; a discharge gate coupled to the hopper, the discharge gate operable to move between a closed position where the discharge gate restricts discharge of lading through the transverse discharge opening and an open position where the discharge gate facilitates lading discharge through the transverse discharge opening; and wherein the orientation of the discharge gate is non-horizontal.
 14. The railcar of claim 13, wherein the discharge gate is pivotally coupled to the hopper and operable to swing between the open position and the closed position.
 15. The railcar of claim 13, wherein the discharge gate is pivotally coupled to the hopper proximate a ridge between the at least two hoppers.
 16. The railcar of claim 13, wherein the discharge gate is slidably coupled to the hopper and operable to slide between the open position and the closed position.
 17. The railcar of claim 13, wherein the discharge gate of a first hopper of the at least two hoppers is offset from horizontal at a different angle than the discharge gate of a second hopper of the at least two hoppers.
 18. The railcar of claim 13, wherein the discharge gate of a first hopper of the at least two hoppers opens in a different direction than the discharge gate of a second hopper of the at least two hoppers.
 19. The railcar of claim 18, wherein the discharge gate of the first hopper and the discharge gate of the second hopper open towards each other.
 20. The railcar of claim 13, wherein the longitudinal distance between adjacent edges of the at least two discharge gates is less than the longitudinal length of the discharge gate. 